Linn KRDS into LK100 and Ground Loop - Help!

We use the Tune Method to evaluate performance

Moderator: Staff

Post Reply
User avatar
El Mero Mero
Active member
Active member
Posts: 107
Joined: 2007-11-04 22:38
Location: Sweden

Linn KRDS into LK100 and Ground Loop - Help!

Post by El Mero Mero »

I have set up a secondary system in the children's living room / play room. The system consists of a KRDS/1 - LK100 - KAN mkI. I am having problems with what sounds like a ground loop. The system is connected to an earthed distribution block. The wall socket is unearthed. I was running this system with a KRDSM/E before and that worked AND sounded really good.

I have tried the following. An unearthed distribution block. Different wall sockets. Using the separate earthing points on the cases. Disconnecting the LAN network. Nothing has worked. The cables are the same as before (Linn Black and K20).

Only once I connected an old LK style Majik-I to use as a preamp the "ground loop" disappeared. But the sound was quite disappointing compared to how the system was sounding with the KRDSM/E . The system is hidden away in one room and the loudspeakers are in another. The rest of the family (and I) would like to use the DVC in this system. Does anyone have any ideas to solve this or what to try?
Spannko
Very active member
Very active member
Posts: 2292
Joined: 2008-01-24 21:46
Location: North East of The Black Country, UK

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by Spannko »

“Children’s living room/play room” - “unearthed wall socket”

Assuming you’re not trolling, which I’d rather you were! Can I suggest that you disconnect everything electrical in the room and employ the services of an electrician as soon as possible?

As far as I am aware, Sweden follows the German electrical code which has the following requirement for domestic earthing:

“Earthing is local, usually through a foundation earthing arrangement. All metallic services shall be bonded (gas and water pipe, heating, waste systems, etc.) with a 10 mm2 . In bathrooms the local equipotential bonding could have a cross sectional area of 4 mm2 . Neutral is re-earthed in the control panel. A protective conductor is distributed to all socket outlets.”
User avatar
lejonklou
Administrator
Administrator
Posts: 6522
Joined: 2007-01-30 10:38
Location: Sweden
Contact:

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by lejonklou »

Those standards are for new houses. Lots and lots of old houses have mains without ground in all rooms except the kitchen.

Regarding the hum in the system, a grounded wall socket won't help. What might is to tie the signal ground to the chassis ground on the source.
User avatar
El Mero Mero
Active member
Active member
Posts: 107
Joined: 2007-11-04 22:38
Location: Sweden

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by El Mero Mero »

Spannko wrote: 2019-10-18 13:52 As far as I am aware, Sweden follows the German electrical code which has the following requirement for domestic earthing.”
As Fredrik has already said. Older houses in Sweden does not necessarily have earthed wall sockets. Our house is from the 1960s. We do have PETsäkrade sockets which makes it a little bit safer.
User avatar
El Mero Mero
Active member
Active member
Posts: 107
Joined: 2007-11-04 22:38
Location: Sweden

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by El Mero Mero »

lejonklou wrote: 2019-10-18 14:07 Regarding the hum in the system, a grounded wall socket won't help. What might is to tie the signal ground to the chassis ground on the source.
How does one tie the signal ground to the chassis ground on the source?
Spannko
Very active member
Very active member
Posts: 2292
Joined: 2008-01-24 21:46
Location: North East of The Black Country, UK

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by Spannko »

lejonklou wrote: 2019-10-18 14:07 Those standards are for new houses. Lots and lots of old houses have mains without ground in all rooms except the kitchen.

Regarding the hum in the system, a grounded wall socket won't help. What might is to tie the signal ground to the chassis ground on the source.
Ah, ok. Thanks.

Just as a matter of interest, how would not having a safety earth affect the musicality of an amplifier?
User avatar
lejonklou
Administrator
Administrator
Posts: 6522
Joined: 2007-01-30 10:38
Location: Sweden
Contact:

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by lejonklou »

El Mero Mero wrote: 2019-10-18 16:26
lejonklou wrote: 2019-10-18 14:07 Regarding the hum in the system, a grounded wall socket won't help. What might is to tie the signal ground to the chassis ground on the source.
How does one tie the signal ground to the chassis ground on the source?
On the rear of your Renew, put something metallic (like a short piece of wire, if you have none a pair of scissors) against the barrel of one of the RCA plugs of the interconnects that lead to the power amp. Then put the other end of the wire (or the other pointy end of the scissors) against the ground screw that I believe is at the rear of all Renews. If there's no ground screw, put it against a screw or an exposed metal part of the case.

Do this with the system powered on. Does the hum go away?

I suspect a better sounding option is to modify the LK100, so that it's signal ground is no longer tied to the case. But that's more complicated.
Spannko wrote: 2019-10-18 18:57Just as a matter of interest, how would not having a safety earth affect the musicality of an amplifier?
You mean the whole system?

We have no safety ground in our new apartment in Uppsala. The house is 100 years old and they have only remade the electricity from the street and to the entry of each apartment, then it's two wires and old outlets after that. SAD!

Regardless of the lack of mains ground, it's really important to use power strips with ground, connected in series if there aren't enough outlets in one. That makes the system sound a lot better, because every case is at the same (floating) potential.

Then I can power the whole system from either the living room wall outlet without ground, or by a really long extension cable from an outlet with ground in the kitchen.

The grounded power from the kitchen is clearly better. It's like a light fog has been removed and the previously loose spikes of the speakers have been tightened.
Spannko
Very active member
Very active member
Posts: 2292
Joined: 2008-01-24 21:46
Location: North East of The Black Country, UK

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by Spannko »

Interesting, thank you.

The electrician I use is experienced with installing “clean earths” for computer rooms and has said that he can convert my HiFi rooms earthing from PME to TT. I’m not sure what difference it will make, but there’s only one way to find out!
User avatar
El Mero Mero
Active member
Active member
Posts: 107
Joined: 2007-11-04 22:38
Location: Sweden

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by El Mero Mero »

lejonklou wrote: 2019-10-18 19:50
El Mero Mero wrote: 2019-10-18 16:26
lejonklou wrote: 2019-10-18 14:07 Regarding the hum in the system, a grounded wall socket won't help. What might is to tie the signal ground to the chassis ground on the source.
How does one tie the signal ground to the chassis ground on the source?
On the rear of your Renew, put something metallic (like a short piece of wire, if you have none a pair of scissors) against the barrel of one of the RCA plugs of the interconnects that lead to the power amp. Then put the other end of the wire (or the other pointy end of the scissors) against the ground screw that I believe is at the rear of all Renews. If there's no ground screw, put it against a screw or an exposed metal part of the case.

Do this with the system powered on. Does the hum go away?

I suspect a better sounding option is to modify the LK100, so that it's signal ground is no longer tied to the case. But that's more complicated.
Thank you Fredrik! The hum is gone. Thank you for sharing your knowledge with us! I will check inside the LK100. Is it as simple as removing the ground from the case?
User avatar
lejonklou
Administrator
Administrator
Posts: 6522
Joined: 2007-01-30 10:38
Location: Sweden
Contact:

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by lejonklou »

Spannko wrote: 2019-10-19 09:42 The electrician I use is experienced with installing “clean earths” for computer rooms and has said that he can convert my HiFi rooms earthing from PME to TT. I’m not sure what difference it will make, but there’s only one way to find out!
Yes! It would be great if you could test and report about this!

I have zero experience with how different earthing systems affect our HiFi.
User avatar
lejonklou
Administrator
Administrator
Posts: 6522
Joined: 2007-01-30 10:38
Location: Sweden
Contact:

Re: Linn KRDS into LK100 and Ground Loop - Help!

Post by lejonklou »

El Mero Mero wrote: 2019-10-19 10:10Thank you Fredrik! The hum is gone. Thank you for sharing your knowledge with us! I will check inside the LK100. Is it as simple as removing the ground from the case?
Great!

No, don't remove the chassis ground. I'm talking about where the signal ground is tied to the chassis, probably through a screw holding the circuit board. And on the board, there are components connecting to the metal around this screw hole. If removing that connection, the signal ground will be floating and my guess is that it will sound better than your current solution.

But the easier solution is that you stick with what you just did; keep the cable between chassis and the barrel of an RCA in place on the rear of the Renew.
Post Reply